Did the Star of Bethlehem really exist? According to the Gospel of Matthew, a bright star appeared in the East, portending the birth of the King of the Jews. Every year around this time, we debate what astronomical phenomenon could have inspired this story. But what's the strongest candidate?

Asking what the Star of Bethlehem really was is like asking what Atlantis really was. Both were simply stories meant to illustrate one author's theological and another author's political beliefs. While they are literary inventions, they certainly may have been inspired by real-life events.

For instance, it's pretty certain that Plato wove into his history of Atlantis details he'd heard of the eruption of Thera and the destruction of the Minoan civilization on Crete. But it's a big — and not entirely justifiable — leap to say that Crete was Atlantis.

Likewise, there are any number of astronomical phenomena that were spectacular and noteworthy enough to have inspired the story of the Star of Bethlehem: novas, conjunctions, comets, etc.

One candidate was suggested a couple of years ago by Australian astronomer David Reneke. He found that there had been a close conjunction of the planets Venus and Jupiter in 2 BC. A conjunction occurs when two or more celestial objects, stars or planets, appear to be very close in the sky. Between 3 and 2 BC, there was a series of spectacular conjunctions, most of them involving the planet Jupiter.

In the case of the conjunction favored by Reneke, Jupiter and Venus would have appeared so close together as to seem to be a single, brilliant star. This would also have appeared near either the Eastern or Western horizon (since Venus is always relatively low in the sky). It also would not have been visible during the day. If we take the story of the Wise Men literally, they would have seen this brilliantly shining object in the eastern sky and might have decided that something of great portent was occurring or about to occur in that direction.

The conjunction of Venus and Jupiter.

Another candidate is yet another spectacular conjunction, this time involving Jupiter and the bright star Regulus. According to Mark Thompson, a fellow of the Royal Astronomical Society, Jupiter and the star appeared close to one another three times in 3 BC and 2 BC. Since the Wise Men were ostensibly astrologers — or at least certainly highly influenced by astrology — seeing the "king of planets" passing so close to a star whose name means "king" or "ruler" on three separate occasions would have been an enormously exciting portent.

A conjunction of Jupiter and Regulus.

And, of course, there are always novas and comets, the latter being an historically important omen of important events (albeit usually bad ones).

Halley's Comet, for instance, made an appearance in 12 BC... a little early, perhaps, but many other comets may have blazed in the night skies during the decades bracketing the turn of the millennium, perhaps making their sole appearance before disappearing forever.

What might have been a large comet was observed by Chinese and Korean astronomers around 5 BC, making it an even better candidate than Halley's Comet. Comets have always been a favorite candidate for Star of Bethlehem hunters: they can seem to hang almost motionless in the sky and can look like enormous arrows, pointing at some target just beyond the horizon.

Finally, it's been suggested by a few researchers that the Star of Bethlehem was a supernova in the Andromeda Galaxy, but this has to remain pure conjecture (at least purer than all the other Christmas star candidates) since it is almost impossible to support by any evidence.

As I said, all of this is interesting, and certainly fun — but only so long as one keeps firmly in mind that it's one thing to talk about what might have inspired the story of the Star of Bethlehem and quite another thing entirely to talk about what it "really" was.